JP5043613B2 - Vehicle with variable toe angle control to detect wheel condition - Google Patents

Description

  The present invention relates to a toe angle variable control type vehicle that variably controls the toe angle of a wheel, and more particularly to a toe angle variable control type vehicle that can detect the state of a wheel by changing the toe angle.

  In general, automobile wheels are fitted with hollow tires on the front, rear, left and right wheels, and filled with compressed air etc. in the hollow portions of the tires to suppress the transmission of impact due to uneven road surface during travel to the vehicle body The ground contact area with the road surface is reduced so that the car can run with a small resistance. However, since the tire is manufactured from an elastic material such as synthetic rubber in order to obtain a frictional force with the road surface, the tire surface gradually wears according to an increase in travel distance or a driver's steering method. In addition, air leaks or punctures may occur due to passing over sharp falling objects on the road or excessive impacts or cornering forces.

  As described above, the tire state changes gradually or instantaneously, but the change in the tire state greatly affects the motion characteristics of the automobile and the maneuverability of the driver. For example, when the surfaces of four tires are evenly worn or the tire pressure is lowered uniformly on the four wheels, the discomfort of the maneuverability given to the driver is small, but the tire performance is remarkably lowered. On the other hand, when such a state is applied to one of the left and right tires, not only the tire performance is lowered, but also the uncomfortable feeling of maneuverability that the driver learns due to the difference in steering characteristics during turning and meandering is increased.

Since the tire condition has a great influence on the maneuverability of the automobile, it is desirable that the tire condition is constantly monitored. Various methods for detecting tire conditions have been proposed so far. For example, a rotating body in which a rotation detection unit such as a gear is formed is integrally provided on a wheel, and the detection result of a detection unit that detects the wheel speed by detecting the passage of the rotation detection unit is compared with a reference value, so that the tire A tire abnormality detection device that determines a state is known (see Patent Document 1).
Japanese Patent Laid-Open No. 10-71819

  However, since the tire abnormality detection device as described above is a method for detecting the difference in tire diameter, it has been difficult to detect a slight decrease in air pressure or a decrease in the tire. Therefore, even if the left and right tires are in different states, such as when emergency spare tires are installed on one of the left and right wheels, or when the cornering force of one of the left and right tires is reduced, The same toe angle control was performed on the wheels as in normal operation. For this reason, there is a difference in steering characteristics between the left turn and the right turn, and there is a problem that the driver feels uncomfortable with the maneuverability.

  The present invention has been made in view of such a background, and in a toe angle variable control type vehicle, it is possible to monitor a minute change in wheel state, and to control even when a state difference occurs between left and right wheels. The purpose is to control the vehicle so that the driver does not feel uncomfortable with respect to sex.

In order to solve the above-mentioned problems, the present invention provides a variable toe angle control vehicle in which an actuator for changing the toe angle of the left and right wheels, a motion state detecting means for detecting a motion state of the vehicle, and a traveling speed of the vehicle are as follows. greater than the predetermined value, when the yaw rate and lateral acceleration of the vehicle is less than the respective predetermined value, the actuator is changed at the same angle wheels of the left and right toe or toe-out, the motion state detecting means at that time Wheel state determination means for determining the state of the wheel based on the detection result is provided. In this case, the motion state detecting means includes a yaw rate detecting means for detecting the yaw rate of the vehicle, a lateral acceleration detecting means for detecting the lateral acceleration of the vehicle, and a damper stroke detecting means for detecting the damper stroke of the vehicle. Of these, at least one may be included. Further, in order to individually change the toe angles of the left and right wheels, the actuators are provided for the left and right wheels, respectively, and the control gains of the left and right actuators are set according to the wheel state determined by the wheel state determining means. It may be configured to further include a control gain setting means.

Further, in order to solve the above-mentioned problems, the present invention provides a left and right electric actuator, which is provided for each of the left and right wheels in the toe angle variable control type vehicle, and individually changes the toe angle of the left and right wheels, Power detection means for individually detecting power required for driving the left and right electric actuators, and when the vehicle traveling speed is greater than a predetermined value and the yaw rate and lateral acceleration of the vehicle are each smaller than a predetermined value, The left and right electric actuators change the left and right wheels to the same angle as toe-in or toe-out, and include wheel state determination means for determining the states of the left and right wheels based on the detection result of the power detection means at that time. Configure. Further, it may be configured to further include control gain setting means for setting control gains of the left and right electric actuators according to the wheel state determined by the wheel state determination means.

  According to the present invention, in a toe angle variable control type vehicle, it is possible to monitor a minute change in wheel state by detecting the motion state of the vehicle when the wheel is changed to toe-in or toe-out. Then, by using the yaw rate detection means, the lateral acceleration detection means, and the damper stroke detection means provided in the vehicle, it is possible to grasp the motion state that is the basis for determining the wheel state. In addition, by providing actuators for the left and right wheels respectively, and setting the control gains for the left and right actuators according to the left and right wheel states, the control gains for the left and right actuators when there is a state difference between the left and right wheels It is possible to individually control the toe angles of the left and right wheels by providing a difference. Thereby, the uncomfortable feeling regarding a driver | operator's vehicle handling property can be reduced.

  In a toe angle variable control type vehicle in which the toe angles of the left and right wheels are individually changed by the left and right electric actuators, by detecting the amount of electric power when the wheels are changed to toe-in or toe-out, Changes can be monitored. Similarly, by setting the control gains of the left and right electric actuators according to the left and right wheel states, if there is a state difference between the left and right wheels, a difference is provided in the control gains of the left and right electric actuators. It is possible to individually control the toe angle of the vehicle, thereby reducing an uncomfortable feeling related to the vehicle maneuverability of the driver.

<< Configuration of Embodiment >>
Hereinafter, an embodiment of a rear wheel toe angle variable control vehicle having a wheel state detection function according to the present invention will be described in detail with reference to the drawings. In the description, for the wheels and members arranged for them, that is, tires, electric actuators, etc., subscripts L or R indicating left and right are attached to the numerals, respectively, for example, rear wheel 5L (left), For example, the rear wheel 5R (right) is referred to as the rear wheel 5.

  FIG. 1 is a schematic configuration diagram of a four-wheeled vehicle according to an embodiment. The toe angle variable control type vehicle V includes front wheels 3L and 3R to which tires 2L and 2R are mounted, and rear wheels 5L and 5R to which tires 4L and 4R are mounted. These front wheels 3L and 3R and rear wheels 5L and 5R are suspended from the vehicle body 1 by left and right front suspensions 6L and 6R and rear suspensions 7L and 7R, each of which includes a suspension arm, a spring, a damper, and the like. The toe angle variable control type vehicle V includes a front wheel steering device 9 that directly steers the left and right front wheels 3L and 3R by steering the steering wheel 8, and left and right trailing arms 10L and 10R in the left and right rear suspensions 7L and 7R. And left and right electric actuators 11L and 11R that individually change the toe angles of the rear wheels 5L and 5R by being individually expanded and contracted.

  The toe angle variable control type vehicle V includes a vehicle speed sensor 13, a yaw rate sensor 14 for detecting yaw rate, and a lateral acceleration sensor 15 for detecting lateral acceleration, in addition to an ECU (Electronic Control Unit) 20 for overall control of various systems. 1 is installed. Further, in the toe angle variable control type vehicle V, damper stroke sensors 16L, 16R, 17L, and 17R for detecting damper stroke displacement amounts of the left and right front and rear suspensions 6L, 6R, 7L, and 7R are provided on the wheels 3L and 3R. , 4L, 4R. In addition to these, various sensors (not shown) are installed in the toe angle variable control type automobile V, and detection signals from the sensors are input to the ECU 20 for vehicle control.

  The ECU 20 includes a microcomputer, a ROM, a RAM, a peripheral circuit, an input / output interface, various drivers, and the like, and an MCU 19 and each sensor described later via a communication line (CAN (Controller Area Network) in this embodiment). 13 to 16 etc. are connected. ECU20 calculates a rear-wheel toe angle based on the detection result of each sensors 13-16, etc., determines the displacement amount of each electric actuator 11L, 11R, and outputs a control signal with respect to MCU19.

  Each of the electric actuators 11L and 11R is a rotary motion / linear motion converter that combines a DC brush motor, a speed reduction mechanism, and a screw mechanism, and is driven and controlled by an MCU (Motor Control Unit) 19. As the actuator, a known appropriate linear displacement electric actuator such as a cylinder device that linearly drives the piston rod with fluid pressure can be used. In this case, it is only necessary to perform tire condition determination using only other determination conditions without using electric power as a tire condition determination condition described later.

  The electric actuators 11L and 11R are respectively provided with stroke sensors 18L and 18R for detecting the stroke position of the output rod. When the signals of the stroke sensors 18L and 18R are input to the MCU 19, feedback control of the electric actuators 11L and 11R by the MCU 19 is performed. As a result, the electric actuators 11L and 11R expand and contract precisely by the amount of displacement, and the rear wheels 5L and 5R change to a desired toe angle.

  The stroke sensors 18L and 18R are constituted by a detected part made of a permanent magnet fixed to the outer peripheral surface of the output rod and a detecting part made of a coil for magnetically detecting the position of the detected part. A known displacement sensor such as a potentiometer can be used for each of the stroke sensors 18L and 18R, but a non-contact type sensor is preferable in consideration of durability.

  According to the rear wheel toe angle variable control type vehicle V configured as described above, the left and right electric actuators 11L and 11R are simultaneously symmetrically displaced, so that the toe-in / to-out of the rear wheels 5L and 5R can be appropriately performed. In addition, if one of the left and right electric actuators 11L and 11R is extended and the other is contracted, both rear wheels 5L and 5R can be steered to the left and right. For example, the rear wheel toe angle variable control type vehicle V has the rear wheel 5 in the same phase as the front wheel steering angle when traveling at high speed and the rear wheel 5 when traveling at low speed, based on the motion state of the vehicle grasped by various sensors. The toe angle is controlled in the opposite phase to the rudder angle, the rear wheel 5 is changed to toe-out during acceleration, and the rear wheel 5 is changed to toe-in during braking so that the driver does not feel uncomfortable with the controllability. Perform angle control.

  FIG. 2 is a block diagram showing a schematic configuration of the rear wheel toe angle variable control type automobile V according to the embodiment. As shown in FIG. 2, the rear wheel toe angle variable control type vehicle V includes a vehicle speed sensor 13, a yaw rate sensor 14, a lateral acceleration sensor 15, front and rear and left and right damper stroke sensors 16, an ECU 20, and a rear wheel toe angle. It is comprised from the control apparatus 30.

  The ECU 20 determines the state of the tire based on the input interface 21 to which the vehicle speed sensor 13, the yaw rate sensor 14, the lateral acceleration sensor 15, the damper stroke sensor 16, the MCU 19 and the like are connected, and the detected values of these sensors 13 to 16 and the like. A toe angle control gain setting unit 23 for setting a control gain for the rear wheel toe angle based on a determination result of the tire state determination unit 22 (wheel state determination unit), the tire state determination unit 22, and a toe angle control gain setting unit A toe angle control amount calculation unit 24 that calculates a control amount of the rear wheel toe angle based on the control gain set by 23 and generates a toe angle control signal, and a toe angle control generated by the toe angle control amount calculation unit 24 The output interface 25 outputs a signal to the rear wheel toe angle control device 30.

  The rear wheel toe angle control device 30 includes left and right electric actuators 11L and 11R, stroke sensors 18L and 18R that detect the strokes of the left and right electric actuators 11L and 11R, and left and right electric actuators based on toe angle control signals output from the ECU 20. It is comprised from MCU19 which drive-controls the electric actuators 11L and 11R. The MCU 19 includes a power detection unit 19a that individually detects powers WL and WR required to drive the left and right electric actuators 11L and 11R, and an input interface of the ECU 20 using the detection result by the power detection unit 19a as an electrical signal. 21 is output.

<< Operation of Embodiment >>
Next, a tire condition monitoring procedure by a rear wheel toe angle control inspection in the rear wheel toe angle variable control type automobile V according to the present embodiment will be described with reference to FIGS. FIG. 3 is a flowchart showing a tire condition monitoring procedure according to the embodiment, and FIG. 4 is a graph showing changes in yaw rate γ, lateral acceleration αy, and electric power W during toe angle control inspection in a normal tire condition. Yes, the horizontal axis represents time t. On the other hand, FIG. 5 is a graph showing changes in yaw rate γ, lateral acceleration αy, and electric power W during toe angle control inspection in an abnormal tire state, and similarly, the horizontal axis represents time t. When a predetermined condition is satisfied during traveling of the toe angle variable control type vehicle V, the ECU 20 executes the following tire state monitoring process in the wheel state determination unit 22, as shown in the flowchart of FIG.

  The ECU 20 first determines whether or not the vehicle speed detected by the vehicle speed sensor 13 is greater than a predetermined speed Va (step 1). When the determination in step 1 is No, the ECU 20 maintains the determination result of the tire condition obtained so far in step 7. On the other hand, if the determination in step 1 is Yes, the ECU 20 determines whether or not the yaw rate detected by the yaw rate sensor 14 is smaller than the predetermined yaw rate γa, and the lateral acceleration detected by the lateral acceleration sensor 15 is equal to the predetermined lateral speed. It is determined whether or not the acceleration αya is smaller. If either the yaw rate or the lateral acceleration is greater than or equal to the predetermined value in step 2, the ECU 20 maintains the determination obtained so far in step 7. On the other hand, if both the yaw rate and the lateral acceleration are smaller than the predetermined values in step 2, the ECU 20 changes the rear wheel 5 to toe-in by a predetermined angle θa as shown in FIG. 4A (step 3).

  At this time, if the rear wheel toe angle variable control type vehicle V is traveling straight, the left and right rear wheels 5L and 5R have tire side slip angles in the vehicle width direction by θa with respect to the traveling direction of the vehicle body 1, respectively. Therefore, a lateral force proportional to the rear wheel toe angle θ acts.

  Here, when the left and right tires 4L, 4R of the rear wheel 5 are in a normal state, the yaw rate γ and the lateral acceleration αy do not change and remain 0 as shown in FIG. On the other hand, for driving the left and right actuators 11L and 11R, the power proportional to the lateral force of the left and right rear wheels 5R and 5L (the state of the left and right rear wheels 5L and 5R is the same and the lateral force generated according to the toe angle is the same). Therefore, as shown in FIG. 4C, the driving power WL, WR having the same magnitude corresponding to the rear wheel toe angle θ is required. It is detected by the power detector 19a.

  In contrast, when the left and right tires 4L, 4R of the rear wheel 5 are in an abnormal state, lateral forces of different magnitudes proportional to the rear wheel toe angle θ are generated in the left and right rear wheels 5L, 5R. Therefore, the rear wheel toe angle variable control type vehicle V loses the straight traveling performance due to the external force of the lateral force difference between the left and right rear wheels 5L and 5R. Therefore, as shown in FIG. 5, even if the same rear wheel toe angle control as in FIG. 4A is performed (FIG. 5A), the yaw rate γ and the lateral acceleration αy are shown in FIG. 5B. Changes in proportion to the lateral force difference between the left and right rear wheels 5L, 5R. On the other hand, since the power difference Wd corresponding to the lateral force difference between the left and right rear wheels 5L, 5R is also generated in the power WL, WR required for driving the left and right actuators 11L, 11R, the power WL, WR is shown in FIG. ).

  Therefore, the ECU 20 determines in step 4 of FIG. 3 whether or not the yaw rate γ during the rear wheel toe angle control inspection is larger than the predetermined value γb. If the answer is No, the ECU 20 proceeds to step 5; Is determined to be abnormal in the tire (step 9). The predetermined value γb is determined by a map created in consideration of the vehicle speed V, the yaw rate γ before and after the rear wheel toe angle control inspection, and other various conditions. Regarding the tire condition determination, a plurality of predetermined values γb are provided in stages, classified according to each stage, and determined as one of various tire conditions after making a comprehensive determination with other elements described later. It is desirable to do.

  In step 5, the ECU 20 determines whether or not the lateral acceleration αy during the rear wheel toe angle control inspection is larger than a predetermined value αyb, the process proceeds to step 6 if the result is No, and to the tire if the result is Yes. It is determined that there is an abnormality (step 9). In step 7, the ECU 20 determines whether or not the drive power difference Wb between the left and right actuators 11L and 11R at the time of the rear wheel toe angle control inspection is larger than a predetermined value Wb. (Step 8). On the other hand, if Yes, it is determined that there is an abnormality in the tire (Step 9), and the determination of the tire state by a series of rear wheel toe angle control inspections is completed, and the process returns to Step 1.

  Next, the procedure of toe angle control according to the embodiment will be described with reference to FIG. The ECU 20 determines whether or not the tire condition obtained by the tire condition monitoring procedure described above is normal in the tire condition determination unit 22 (step 11). If the determination in step 11 is No, the ECU 20 calculates the control gains of the left and right rear wheels 5L and 5R based on the difference in tire condition in the toe angle control gain setting unit 23 (step 12), and then proceeds to step 13. move on. If the determination in step 11 is Yes, the process proceeds directly to step 13.

  In step 13, the ECU 20 multiplies the toe angles of the left and right rear wheels 5L, 5R calculated by the above-described normal rear wheel toe angle control by the control gain obtained in step 12 in the toe angle control amount calculation unit 24. Then, correction based on the tire condition difference is performed (step 13), and a control signal corresponding to the corrected left and right rear wheel toe angles is output to the MTU 19 via the output interface 25 to drive and control the left and right electric actuators 11L and 11R. .

  In the present embodiment, by adopting such a configuration, in the rear wheel toe angle variable control type vehicle V, when the rear wheel 5 is changed to toe-in, the yaw rate γ, the lateral acceleration αy, and the driving power of the electric actuator 11 are changed. By detecting this, it is possible to monitor minute changes in the tire condition such as a change in diameter due to wear and a decrease in air pressure. By using the yaw rate sensor 14, the lateral acceleration sensor 15, and the power detection unit 19 a provided in the vehicle body 1, it is possible to grasp the motion state and the drive power that are the basis for determining the tire state. Further, the electric actuator 11 is provided for the left and right rear wheels 5L and 5R, and the control gains of the left and right actuators 11L and 11R are set according to the left and right tire states, so that the left and right rear wheels 5L and 5R are in a state. When a difference occurs, it is possible to improve the steering performance of the vehicle by providing a difference in the control gain of the left and right electric actuators 11L and 11R and individually controlling the toe angles of the left and right rear wheels 5L and 5R. It has become. Thereby, the uncomfortable feeling about a driver | operator's vehicle controllability is reduced.

This is the end of the description of specific embodiments. However, aspects of the present invention are not limited to these embodiments. For example, in the above-described embodiment, the toe angle control is performed only on the rear wheel to determine the tire state of the rear wheel, but the toe angle control may be applied to the front wheel or all four wheels. In the above embodiment, the yaw rate sensor and the lateral acceleration sensor are used as a basis for determining the wheel state by grasping the motion state of the vehicle, but the damper stroke sensors provided on the front, rear, left and right wheels are used. Alternatively, other sensors may be used. Alternatively, only one of the yaw rate sensor and the lateral acceleration sensor may be used. Furthermore, in the above embodiment, the tire wear degree and the air pressure are set as the determination targets as the wheel state.For example, changes other than the above in the tire, such as the tire balance and the wheel shaft, and the change in the wheel itself are determined. Modifications can be made as appropriate without departing from the spirit of the present invention.

Schematic configuration diagram of an automobile according to an embodiment The block diagram which shows schematic structure of the rear-wheel toe angle control apparatus which concerns on embodiment. The flowchart which shows the monitoring procedure of the tire condition which concerns on embodiment A graph showing changes in the exercise state and power during toe angle control inspection under normal tire conditions A graph showing the change in the exercise state and power during the toe angle control inspection in an abnormal tire state The flowchart which shows the procedure of the toe angle control which concerns on embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body 4 Front wheel 5 Rear wheel 11 Electric actuator 14 Yaw rate sensor 15 Lateral acceleration sensor 16 Damper stroke sensor 19 MCU (Motor Control Unit)
19a Electric power detection unit 20 ECU (Electronic Control Unit)
22 Tire condition determination unit (wheel condition determination means)
23 Toe angle control gain setting unit 24 Toe angle control amount calculation unit V Rear wheel toe angle variable control type automobile

Claims (5)

An actuator that changes the toe angle of the left and right wheels;
Motion state detection means for detecting the motion state of the vehicle;
When the travel speed of the vehicle is greater than a predetermined value and the yaw rate and lateral acceleration of the vehicle are each smaller than a predetermined value, the actuator changes the left and right wheels to the same angle as toe-in or toe-out . A toe angle variable control type vehicle comprising wheel state determination means for determining a state of the wheel based on a detection result of the motion state detection means.   The motion state detection means includes at least one of a yaw rate detection means for detecting a yaw rate of the vehicle, a lateral acceleration detection means for detecting a lateral acceleration of the vehicle, and a damper stroke detection means for detecting a damper stroke of the vehicle. The toe angle variable control type vehicle according to claim 1, comprising one. The actuators are respectively provided for the left and right wheels to individually change the toe angles of the left and right wheels,
The toe angle according to claim 1 or 2, further comprising control gain setting means for setting control gains of the left and right actuators according to a wheel state determined by the wheel state determination means. Variable control vehicle. Left and right electric actuators that are respectively provided for the left and right wheels and individually change the toe angles of the left and right wheels;
Power detection means for individually detecting power required for driving the left and right electric actuators;
When the vehicle traveling speed is greater than a predetermined value and the yaw rate and lateral acceleration of the vehicle are each smaller than a predetermined value, the left and right electric actuators change the left and right wheels to the same angle to toe-in or toe-out , A toe angle variable control type vehicle comprising wheel state determination means for determining the states of the left and right wheels based on the detection result of the power detection means at that time .   5. The toe angle variable control type according to claim 4, further comprising control gain setting means for setting control gains of the left and right electric actuators according to the wheel state determined by the wheel state determination means. vehicle.

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